1. Field of the Invention
The present invention relates to power line communications, and more particularly, to a technique for blocking a portion of energy of a signal, e.g., a spurious signal in a power line.
2. Description of the Related Art
Power line communications systems may send data signals over multiple sets of proximate lines, such as medium voltage and low voltage lines strung on the same utility poles or multiple sets of lines of the same voltage class on the same poles. Over distances of hundreds of meters, there can be significant induction of signal from one set of lines to another, and these induced signals can appear to modem receivers as background noise.
To some extent, the induced signal strength is a function of the cumulative distance that the lines run together. This induced signal, which is a spurious signal, can be attenuated by interrupting the continuity of the line for the relevant frequencies. This interruption can be achieved by attaching filters in series with the lines, the filters having a high impedance at the frequencies of interest. Usually, interrupting a power line circuit and service to customers is unacceptable.